Colour polymorphic Gouldian finches avoid complex backgrounds but prefer simple camouflage colours over white backgrounds

Many animals blend in well with their environment known as camouflage which is a successful predator avoidance strategy. However, captive environments often do not allow for camouflage and may result in stress and reduced welfare. We investigated whether colour polymorphic Gouldian finches use background matching or complex backgrounds as a camouflage strategy. Birds were tested in unfamiliar cages with half of the cage with one background and the other half with another background. The time spent in front of each background was measured. The first experiment compared a simple green background versus a complex patterned background consisting of red, green and black shapes, whereas the second experiment compared a simple green background against a white background which is often used in cages. Backgrounds were swapped after 10 days to control for site preferences (phase 1 and 2). In both experiments all birds clearly preferred the simple green background. Diverting habituation processes were observed in the second experiment with black-headed birds visiting the white background more during phase 1 than phase 2, whereas the opposite was the case for the red-headed birds. In the first experiment, preference for open habitats may have interfered with optimal background matching. The second experiment showed that white backgrounds are aversive for the birds. Different habituation speeds are consistent with differences in exploration and risk-taking between the head colour morphs. The results show that 2D background colours are a simple but effective enrichment to increase welfare in birds.